Rapid-setting rigid polyurethanes have previously been prepared; however, such processes have required the presence of a catalyst for urethane formation, a modifier substance or both. Illustrative of such processes are U.S. Pat. No. 3,378,511; U.S. Pat. No. 3,726,827; U.S. Pat. No. 3,746,692; U.S. Pat. No. 3,773,697, U.S. Pat. No. 3,801,532; U.S. Pat. No. 3,847,859; U.S. Pat. No. 3,878,156; U.S. Pat. No. 3,787,157; U.S. Pat. No. 3,879,329; U.S. Pat. No. 3,882,071; U.S. Pat. No. 3,882,072; U.S. Pat. No. 3,883,465; U.S. Pat. No. 3,883,466; U.S. Pat. No. 3,883,484; U.S. Pat. No. 3,886,102; U.S. Pat. No. 3,886,182; and U.S. Pat. No. 3,892,705. Each of the above patents disclose a process which requires the presence of both a modifier compound and a catalyst for urethane formation in order to prepare rapid-setting polyurethanes except U.S. Pat. No. 3,773,697 and U.S. Pat. No. 3,726,827, which do not require the presence of a modifier and additionally, U.S. Pat. No. 3,773,697, requires a fluid quench step after solidification. A copending application, Ser. No. 405,244 filed Oct. 10, 1973, now U.S. 4,001,166 of which the applicant herein is an applicant therein discloses a process for preparing rapid-setting polyurethanes without a catalyst; however, an amine-containing polyol and a modifier are required. Also, another copending application Ser. No. 456,093 filed Mar. 29, 1974, now U.S. Pat. No. 4,008,185 which the applicant herein is the applicant therein discloses a process for preparing rapid-setting polyurethanes without a catalyst; however, a non-amine, nitrogen-containing compound such as an amide is required to be present as a modifier.